Sizing of textile fibers with polyvinyl alcohol (PVOH) is well known in the art. PVOH with a degree of hydrolysis in the range of 87 to 100 mole % has proven effective in practice as a sizing agent.
Essentially all textile warp size compositions for spun yarns contain a hydrophobic waxy material, such as hydrogenated tallow wax in order to impart lubricity during weaving and to lessen both sticking to the drying cans and build-up during slashing.
In addition, such waxes are difficult to remove from the woven product prior to finishing. Special solvent extraction steps are sometimes used or finishing mills must accept a high percentage of second quality. Frequently wax spots left on the cloth result in dye defects.
Moreover, finishing mills are interested in lowering the temperature of the aqueous size removal systems which causes further removal problems with wax.
Further, foaming problems during sizing are observed whenever the degree of hydrolysis of the polyvinyl alcohol is below 99% and such problems increase with decreasing hydrolysis level. The presence of foam leads to uneven sizing with the result being a decrease in weaving efficiency. Foaming can be eliminated through the use of superhydrolyzed PVOH (degree of hydrolysis 99-100%) or by the use of defoamers.
The use of superhydrolyzed PVOH in sizing operations, however, imparts other problems such as brittleness of the sizing film which in turn leads to excessive shedding and reduced weaving efficiency. The film properties and adhesion to the fibers can be increased through the addition of polyacrylates, polyesters, polyglycerols and the like.
The film properties and the adhesion to the fibers of partially hydrolyzed PVOH (hydrolysis 85-96 mole %) are superior to those exhibited by superhydrolyzed PVOH. Further, the desizing can be accomplished at a lower temperature, due to decreased crystallinity of the PVOH, leading to an energy savings. Foaming during the sizing operation, however, has to a great extent prevented partially hydrolyzed PVOH grades from penetrating the sizing market despite the above advantages.
The foaming of aqueous sizing compositions containing partially hydrolyzed PVOH can, in many operations, be successfully overcome through the addition of defoamers such as Colloid 694, 693 or 513, Drew Y-281, Nopco NXZ L, Foammaster VL defoamers or certain ethylene oxide-propylene oxide adducts with a high level of propylene oxide. However, the presence of a hydrophobic waxy material in the typical aqueous sizing compositions will have a pronounced and detrimental effect on the performance of the above-mentioned defoamers. Thus, the foaming problem has, to a great extent, excluded PVOH products having a lower degree of hydrolysis from use in sizing compositions despite the mentioned advantages.
Japanese Patent Publication No. 47-45634 discloses a method for warp sizing polyamide synthetic fiber which comprises treating synthetic polyamide fiber with a warp-sizing composition comprising PVOH, a highly hydroscopic anionic surfactant and a nonionic surfactant which is lowfoaming polypropylene glycol-ethylene oxide adduct and/or monoester thereof. Example 1 (test 2) shows, in the absence of the anionic component, there is desizing in the weaving operation.
U.S. Pat. No. 4,389,506 discloses a process for the preparation of a substantially dust-free PVOH powder comprising contacting the PVOH with about 0.5 to 4% polyglycol. This document states that block copolymers containing the constituents of polyethylene glycol with propylene oxide in which the oxyethylene content predominates (more than 50%) are, to a lesser extent, suitable as long as the end-use properties of the PVOH are not adversely affected. Composition B in Example I shows PVOH plus 1% Pluronic F98 surfactant.
U.S. Pat. No. 4,428,751 discloses a process for the wet processing of textile materials which comprises applying to the textile material an aqueous textile-treating liquor containing a textile-treating component in an amount sufficient to provide a desired effect on the textile material, and further containing in an amount sufficient to provide foam control properties, a foam control agent of the formula ##STR1## where y is 0 or 1; m and n are both independently an integer from 0 to 30 with the proviso that the sum of y+m+n must be at least 1; a and b are independently an integer from 1 to 7; R is a C.sub.1- C.sub.40 aliphatic group; R.sub.1 is a C.sub.1- C.sub.16 alkyl group, a C.sub.1- C.sub.7 alkoxy group or a C.sub.3- C.sub.8 alkoxyalkyl group; and Z is hydrogen, halogen, phosphate or phosphite.
South African Patent 712671 discloses a jute sizing composition which comprises a dilute aqueous solution of PVOH which has been hydrolyzed to at least about 85% and a water soluble glycol selected from the group consisting of polyethylene glycol and polypropylene glycol.
U.S. Pat. No. 3,634,295 discloses a sizing composition for man-made yarns comprising a PVOH and a polyacrylic acid.
U.S. Pat. No. 3,804,785 discloses aqueous solutions of PVOH containing amylose and/or amylitol of low molecular weight for sizing paper and textile fibers.
U.S. Pat. No. 4,222,922 discloses a warp size for filament yarn consisting essentially of PVOH, alkylphenoxy (or cresoxy) ethoxyethyl dimethylbenzyl ammonium chloride and a plasticizer such as glycerol or urea.
U.S. Pat. No. 4,251,403 discloses a warp size for filament yarn consisting essentially of PVOH, urea and mono- and di-saccharides, such as sucrose.
U.S. Pat. No. 4,309,510 discloses a sizing composition consisting of a PVOH and 1-30 wt % of an amine oxide.
U.S. Pat. No. 4,383,063 discloses a PVOH based sizing solution containing a small amount of a quaternary (e.g., dialkyldimethyl) ammonium salt or quaternary imidazolinium salt additives.
U.S. Pat. No. 4,399,245 discloses a sizing composition consisting substantially of PVOH and polyglycerol.